.travis.yml in image_optim_rails-0.4.1 vs .travis.yml in image_optim_rails-0.4.2

@@ -3,36 +3,37 @@
 cache:
   bundler: true
   directories:
     - $(npm root)
     - ~/bin
+rvm:
+  - '1.9.3-p551'
+  - '2.0.0-p648'
+  - '2.1.10'
+  - '2.2.10'
+  - '2.3.8'
+  - '2.4.6'
+  - '2.5.5'
+  - '2.6.3'
 script:
-  - bundle exec image_optim --info
-  - bundle exec rspec
+  - ./bundle exec image_optim --info
+  - ./bundle exec appraisal rspec
 before_install:
+  - gem install rubygems-update || gem install rubygems-update --version '< 3'
+  - gem update --system
+  - gem install bundler --version '< 2'
+  - ruby -e 'puts "#!/bin/sh", %{bundle _#{Gem::Dependency.new("bundler", "< 2.0").to_spec.version}_ "$@"}' > bundle
+  - chmod +x bundle
   - mkdir -p ~/bin
-  - command -v svgo || npm install svgo
-  - command -v pngout || curl -L "http://static.jonof.id.au/dl/kenutils/pngout-20130221-linux.tar.gz" | tar -xz -C ~/bin --strip-components 2 --wildcards '*/x86_64/pngout'
+  - command -v svgo || npm install -g svgo
+  - command -v pngout || curl -L "http://static.jonof.id.au/dl/kenutils/pngout-20150319-linux.tar.gz" | tar -xz -C ~/bin --strip-components 2 --wildcards '*/x86_64/pngout'
+install:
+  - ./bundle install --jobs=3 --retry=3
+  - ./bundle exec appraisal install --jobs=3 --retry=3
 matrix:
   include:
-    - env: RAILS_VERSION='~> 3.2'
-      rvm: '1.9.3-p551'
-    - env: RAILS_VERSION='~> 4.0' SPROCKETS_RAILS_VERSION='~> 2.0'
-      rvm: '2.0.0-p648'
-    - env: RAILS_VERSION='~> 4.0' SPROCKETS_VERSION='~> 3.0'
-      rvm: '2.0.0-p648'
-    - env: RAILS_VERSION='~> 4.0' SPROCKETS_VERSION='>= 4.0.beta'
-      rvm: '2.0.0-p648'
-    - env: RAILS_VERSION='~> 5.0' SPROCKETS_RAILS_VERSION='~> 2.0'
-      rvm: '2.2.7'
-    - env: RAILS_VERSION='~> 5.0' SPROCKETS_VERSION='~> 3.0'
-      rvm: '2.2.7'
-    - env: RAILS_VERSION='~> 5.0' SPROCKETS_VERSION='>= 4.0.beta'
-      rvm: '2.2.7'
     - env: RUBOCOP=✓
-      rvm: '2.4.1'
+      rvm: '2.6.3'
       script: bundle exec rubocop
-      before_install:
     - env: CHECK_RUBIES=✓
-      rvm: '2.4.1'
+      rvm: '2.6.3'
       script: bundle exec travis_check_rubies
-      before_install: